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The JavaScript JSON Cookbook

The JavaScript JSON Cookbook

By : Ray Rischpater, Brian Ritchie
1 (2)
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The JavaScript JSON Cookbook

The JavaScript JSON Cookbook

1 (2)
By: Ray Rischpater, Brian Ritchie

Overview of this book

If you're writing applications that move structured data from one place to another, this book is for you. This is especially true if you've been using XML to do the job because it's entirely possible that you could do much of the same work with less code and less data overhead in JSON. While the book's chapters make some distinction between the client and server sides of an application, it doesn't matter if you're a frontend, backend, or full-stack developer. The principles behind using JSON apply to both the client and the server, and in fact, developers who understand both sides of the equation generally craft the best applications.
Table of Contents (12 chapters)
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11
Index

Making an asynchronous request for data

You use the instance of the XMLHttpRequest class you created to request data. You can request data using any HTTP method; typically you'll use GET or POST. GET is good if you don't need to pass any arguments, or if the arguments are encoded in the service URL; POST is necessary if you're going to post JSON to the server as arguments for your server-side script.

How to do it...

Continuing to enhance our client page script's doAjax function, here's how to issue an asynchronous request, modifying the previous example:

function doAjax() {
  var xmlhttp;
  if (window.XMLHttpRequest)
  {
    // code for IE7+, Firefox, Chrome, Opera, Safari
    xmlhttp=newXMLHttpRequest();
  
    xmlhttp.open("POST","/", true);
    xmlhttp.send("");
  }
}

How it works…

The XMLHttpRequest class has two methods you use to make a request: open and send. You use the open method to start the process of issuing the request...

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